Reproducibility of the lipids over a 6-week period, stratified by lipid class. Reproducibility of individual lipids within each class in plasma (blue) and erythrocytes (red); bars represent the median intraclass correlation coefficient (ICC) of the lipid class. Abbreviations: ICC = intraclass correlation coefficient, CE = cholesteryl ester, CER = ceramide, DAG = diacylglycerol, DCER = dihydroceramide, FFA = free fatty acid, HCER = hexosylceramide, LCER = lactosylceramide, (L)PC = (lyso)phosphatidylcholines, (L)PE = (lyso)phosphatidylethanolamine, SM = sphingomyelin, TAG = triacylglycerol.